Furnace-sheet for steam-boilers



(Model.)

f 2 Sheets-Sheet 1. H. G, DARBY. FRNAGE SHEET EUR STEAM BOILERS.

y No. 253,516.

y Patented Peb. 14,1882..

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(Model.) y 2 Sheets-Sheet 2.

H. C. BARRY.

FURNAGE SHEET FOR STEAM -BOILERS.

i -'NCL 253.516. v f "Patentedf'eh11151882.

" UNITED STATES PATENT Carica. y

HENRY o. DARBY, or wYANDorTE, Kansas.

FU RNACEfSH EET FOR STEAM-BOILERS.

'SPECIFICATION forming part of Letters PatentNo. 253,516, dated February14, 1882.

Application ilcd January 28, 1881. (Model.) I

To all whom it may concern Be it known that I, HENRY 0.7DARBY, oflVyandotte, county of Wyandotte, and State of Kansas, have invented anew and useful Improvement in Furnace-Sheets for Steam-Boilers, of whichthe following is a speciication.

The invention relates to the construction of furnace-sheets, and has forits object the means of so distributing and localizing the tension dueto expansion and contraction of metal by changesin temperature as torelieve stay-bolts from lateral strain and prevent cracking anddestruction ot' sheets.

The improvement consists in a series ofshallow spherical depressions orpocketsrolled or hammered into that part ot' furnace-sheet suhject tothe most violent temperature. These depressions present on the oppositeside of sheet -corresponding spherical projections. They are arranged inseries at right angles to each other,and are placedas close tooneanother as may in practice be found compatible with the easiest curve towhich the material of the sheet can be molded at their junction.(lentral and intermediate to each group of four projections a stay-boltpasses through furnacesheet, connecting it with the outside shell ofboiler, as shown on drawings. The size of the elevations is governed bythe distance of the stay-bolts from center to center. The sheets are soplaced in boiler that the depressions or pockets face the water-space,while the elevations on its opposite side face the tire of the furnace.

In the drawings, Figure 1 shows a plan of m-y-furnace-sheet with aseries of elevations, central to each four of which a stay-bolt isplaced, joining the furnace and outside sheet together. Fig. 2 is asideelevation of same, and Fig. 3 is a vertical section through theelevations. Fig. 4 is an enlarged sectional Aview of theshee't, showingstay-bolts in position. .Fig 5is a longitudinal section of alocomotive-boiler with device applied to the side sheets, and Fig. 6 isa horizontal section on line A B, showing relative position ofthe sheetto the water-space and furnace.

The object of the spherical projections herein described is to formelastic centers for taking up the expansion and contraction of metalimmediately con-fined by stay-bolts surrounding it.

The advantages I claim for my furnacesheet are its elasticity for takingup the expansion of metal by heat and equalizing the strain on thesurrounding stay-bolts; secondly, its superior strength due to itsstructure. This renders less bracing necessary than formerly, wherebystay-bolts may be placed at greater intervals from each other withperfect safety.

The elevations on sheet being arranged in lines running at right anglesto eachother form, so to speak, a system of vertical and horizontalcorrugations which perfectly equalize the strain on stay-bolts by takingup the expansion ot' metal, thus preventing their becoming loose, andavoiding the destruction ot' sheet by cracking.

I would, in this connection, remark upon the difference between myimprovement and such known under the name ot sheets. In the corrugatedsheets the grooves cannot be so disposed as to compensate for theopposing forces of expansion and contraction equally in all directions.The strain or tension is relieved either in vertical or horizontallines, according to the direction of the corrugations, and as asymmetrical disposition ot' the two systems of corrugations-z'. e.,vertical and horizontal-such as would equalize the strain in alldirections is impractical, it follows that in such a combination of thetwo, as specified in Patent No. 7,519, Reissue, unequal local strainmust result, due to the unequal distribution ot' the corrugations. Suchlocal lateral strain will be exerted to a great extent in diagonallines.

I desire also to state that I lay no claim to sheets provided withcup-form ed projections which open into the tire-box, such assubstantially described in English Patent No. 4l of 1852. Such a devicewould be entirely impractical for my purpose. Both in object and mannerot' construction, as Well as in application, marked differences existbetween myimprovement and that of Patent No. 41, mentioned. In the onecase heating-area is the sole object in View, and the construction ofthe corru gated sheetis subordin ated to that idea alone. In the otherthe increased heating-surface is merely an incidental and unimportantresult of the main object. In the one the recesses are very deep andpronounced; they are separated by largeintervals and the projections arepresented to the Water-space, thus contracting its capacity. In theother the rccessesare shallow or saucer-shaped, such as may be producedby rolling or hammering the sheet on suitable patterns Withoutsubjecting the metal to an undue amount of strain. The depressions are.closely grouped in lines at right angles to each other, and beingpresented to the water-space of' boiler increase its capacit-y. rlheseare thc differences in theconstruction. In the application thedifferences are even more pronounced, for, owing to the marked intervalsbetween the depressidns, the sheets are practically rigid andunyielding, abrding no reliefl to the strain on the stay-bolts Whatever.

VVhat I desire to claim as my invention is A furnace-sheet for re-boxes,presenting on its anterior surface, or that side facing the water-space,a series ot' shallow spherical depressions or recesses closely groupedin lines at right angles to each other, and on its posterior surface, orthat presented to the furnace,

a series of raised or projecting surfaces corresponding tothedepressions tirst mentioned, for the purposes and objects named, andsubstantially as described.

HENRY C. DARBY. Witnesses:

WILLIAM J ANDUs, JAMEs D. KUsfrAL.

